Gram-Scale Synthesis of Chain-Deuterated Sphingosine and Its Derivatization to Produce Ceramide,Sphinganine and Sphingosine-1-phosphate

Sphingosine plays crucial roles in various cellular functions. Deuterated molecules are widely used as the important tools to explore the structure, property, and function of biochemical materials. We here report a gram-scale synthesis of sphingosines with different deuterated chains. The synthesis started from different protiated fatty acids, which underwent hydrothermal platinum-catalyzed hydrogen/deuterium (H/D) exchange to produce the deuterated chains with different length. The Horner–Wadsworth–Emmons (HWE) coupling of a chiral amino acid derivative with the deuterated chains generated the unsaturated ketone precursors. The following stereoselective reduction via cyclic Felkin–Anh transition led to the desired anti-amino alcohol geometry. This efficient protocol enabled the gram-scale synthesis of the chain-deuterated sphingosines. The subsequent synthesis of the chain-deuterated derivatives, i. e. ceramide, sphinganine and sphingosine-1-phosphate, is also described. Their deuterium content was simultaneously characterized by ¹H NMR and high-resolution mass spectrum (HRMS).     

Enantioselective Synthesis of 3-Heterosubstituted-2-amino-1-ols by Sequential Metal-Free Diene Aziridination/Kinetic Resolution

A general protocol for the enantioselective synthesis of 3-heterosubstituted-2-amino-1-ols was developed based on metal- free intramolecular regio- and stereoselective diene aziridination and regioselective opening. Kinetic resolution of the resulting (1′-NR¹R² and 1′-SR)-4-oxazolidinones was performed using ABCs organocatalysts, expanding the application of this methodology.     

UHPLC–MS/MS analysis of sphingosine 1‐phosphate in joint cavity dialysate and hemodialysis solution of adjuvant arthritis rats: Application to geniposide pharmacodynamic study

Geniposide (GE) is an iridoid glycoside compound with anti‐inflammatory effect. The potential of sphingosine 1‐phosphate (S1P) as a plasma marker in human diseases was suggested recently in the literature, which demonstrated that, in patients with inflammatory diseases, plasma S1P was elevated. It follows that the obstructive coronary artery disease can be predicted with serum S1P. Therefore, S1P can also be potentially used as a pharmacodynamic marker to study adjuvant arthritis (AA) rats. In the current study, a UHPLC–MS/MS method combined with the microdialysis sampling technique (using FTY720 phosphate as an internal standard) was adopted and validated to measure S1P levels in the hemodialysis fluid and joint cavity dialysates of AA rats after oral administration of GE. A S1P concentration–time curve in the dialysate was established in this study. It was demonstrated that GE exerted an anti‐inflammatory effect by reducing AA‐induced elevated S1P levels. It is showed that changes in S1P concentrations over time can be used to monitor the pharmacodynamic effects of GE in treating AA rats in pharmacodynamic studies.     

Synthesis of PP2A-Activating PF-543 Derivatives and Investigation of Their Inhibitory Effects on Pancreatic Cancer Cells

Sphingosine kinase (SK) is involved in the growth of cells, including cancer cells. However, which of its two isotypes—SK1 and SK2—is more favorable for cancer growth remains unclear. Although PF-543 strongly and selectively inhibits SK1, its anticancer effect is not high, and the underlying reason remains difficult to explain. We previously determined that the tail group of PF-543 is responsible for its low metabolic stability (MS). In this study, compounds containing aromatic or aliphatic tails in the triazole group were synthesized, and changes in the SK-inhibitory effect and anticancer activity of PF-543 were assessed using pancreatic cancer cells. The compounds with aliphatic tails showed high inhibitory effects on pancreatic cancer cells but slightly lower selectivity for SK1. A compound with an introduced aliphatic tail activated protein phosphatase 2A (PP2A), showing an effect similar to that of FTY720. Molecular docking analysis revealed that the PP2A-binding form of this newly synthesized compound was different from that noted in the case of FTY720. This compound also improved the MS of PF-543. These results indicate that the tail structure of PF-543 influences MS.     

Benzoxazolone Carboxamides: Potent and Systemically Active Inhibitors of Intracellular Acid Ceramidase

The ceramides are a family of bioactive lipid‐derived messengers involved in the control of cellular senescence, inflammation, and apoptosis. Ceramide hydrolysis by acid ceramidase (AC) stops the biological activity of these substances and influences survival and function of normal and neoplastic cells. Because of its central role in the ceramide metabolism, AC may offer a novel molecular target in disorders with dysfunctional ceramide‐mediated signaling. Here, a class of benzoxazolone carboxamides is identified as the first potent and systemically active inhibitors of AC. Prototype members of this class inhibit AC with low nanomolar potency by covalent binding to the catalytic cysteine. Their metabolic stability and high in vivo efficacy suggest that these compounds may be used as probes to investigate the roles of ceramide in health and disease, and that this scaffold may represent a promising starting point for the development of novel therapeutic agents.     

A Click Cage: Organelle‐Specific Uncaging of Lipid Messengers

Lipid messengers exert their function on short time scales at distinct subcellular locations, yet most experimental approaches for perturbing their levels trigger cell‐wide concentration changes. Herein, we report on a coumarin‐based photocaging group that can be modified with organelle‐targeting moieties by click chemistry and thus enables photorelease of lipid messengers in distinct organelles. We show that caged arachidonic acid and sphingosine derivatives can be selectively delivered to mitochondria, the ER, lysosomes, and the plasma membrane. By comparing the cellular calcium transients induced by localized uncaging of arachidonic acid and sphingosine, we show that the precise intracellular localization of the released second messenger is crucial for the signaling outcome. Ultimately, we anticipate that this new class of caged compounds will greatly facilitate the study of cellular processes on the organelle level.     

微流控芯片电泳分离血清中小而密低密度脂蛋白的研究

应用微流控芯片电泳,以40 mmol/L Tricine(pH9.8)作为电泳缓冲体系,十二烷基硫酸钠(SDS)作为添加剂(0.1 mmol/L SDS样品溶液,0.02 mmol/L SDS分离缓冲液),分离血清小而密低密度脂蛋白(sdLDL)。研究荧光染料硝基苯并噁二唑-C6-酰基鞘胺醇(NBD C6-ceramide)与脂蛋白结合的特异性、饱和性以及血清保存和检测时间对脂蛋白电泳行为的影响;探讨SDS有效降低蛋白吸附,提高血清脂蛋白分辨率的作用。冠心病(CHD)组sdLDL检出率(75%)显著高于对照组(6%,P<0.01)。该法具有简易、快速、高效等优点,可望成为CHD危险性评估的常规分析手段。     

ST-2191, an Anellated Bismorpholino Derivative of Oxy-Fingolimod,Shows Selective S1P1 Agonist and Functional Antagonist Potency In Vitro and In Vivo

Sphingosine 1-phosphate (S1P) is an extensively studied signaling molecule that contributes to cell proliferation, survival, migration and other functions through binding to specific S1P receptors. The cycle of S1P₁ internalization upon S1P binding and recycling to the cell surface when local S1P concentrations are low drives T cell trafficking. S1P₁ modulators, such as fingolimod, disrupt this recycling by inducing persistent S1P₁ internalization and receptor degradation, which results in blocked egress of T cells from the secondary lymphoid tissues. The approval of these compounds for the treatment of multiple sclerosis has placed the development of S1PR modulators in the focus of pharmacological research, mostly for autoimmune indications. Here, we report on a novel anellated bismorpholino derivative of oxy-fingolimod, named ST-2191, which exerts selective S1P₁ agonist and functional antagonist potency. ST-2191 is also effective in reducing the lymphocyte number in mice, and this effect is not dependent on phosphorylation by sphingosine kinase 2 for activity. These data show that ST-2191 is a novel S1P₁ modulator, but further experiments are needed to analyze the therapeutic impact of ST-2191 in animal models of autoimmune diseases.     

Efficient Syntheses of a Series of Glycosphingolipids with 1,2‐trans‐Glycosidic Linkages

A series of glycosphingolipids with 1,2‐trans‐glycosidic linkages were synthesized in the presence of neighboring group participation using trichloroacetimidates as glycosyl donors and an azido‐sphingosine as the glycosyl acceptor. During the preparation of the target compounds, it was found that the α‐L‐arabinopyranosyl unit in target 7e and intermediates 7b–7d existed in the ¹ C ₄ conformation and that the β‐L‐fucopyranosyl unit in 10e adopted the ⁴ C ₁ conformation.